Collect room-version variations into one place (#4969)

Collect all the things that make room-versions different to one another into
one place, so that it's easier to define new room versions.

4 files changed, 27 insertions, 25 deletions

diff --git a/synapse/federation/federation_base.py b/synapse/federation/federation_base.py
index a7a2ec4523..dfe6b4aa5c 100644
--- a/synapse/federation/federation_base.py
+++ b/synapse/federation/federation_base.py
@@ -20,8 +20,9 @@ import six
 from twisted.internet import defer
 from twisted.internet.defer import DeferredList
 
-from synapse.api.constants import MAX_DEPTH, EventTypes, Membership, RoomVersions
+from synapse.api.constants import MAX_DEPTH, EventTypes, Membership
 from synapse.api.errors import Codes, SynapseError
+from synapse.api.room_versions import KNOWN_ROOM_VERSIONS, EventFormatVersions
 from synapse.crypto.event_signing import check_event_content_hash
 from synapse.events import event_type_from_format_version
 from synapse.events.utils import prune_event
@@ -274,9 +275,12 @@ def _check_sigs_on_pdus(keyring, room_version, pdus):
     # now let's look for events where the sender's domain is different to the
     # event id's domain (normally only the case for joins/leaves), and add additional
     # checks. Only do this if the room version has a concept of event ID domain
-    if room_version in (
-        RoomVersions.V1, RoomVersions.V2, RoomVersions.STATE_V2_TEST,
-    ):
+    # (ie, the room version uses old-style non-hash event IDs).
+    v = KNOWN_ROOM_VERSIONS.get(room_version)
+    if not v:
+        raise RuntimeError("Unrecognized room version %s" % (room_version,))
+
+    if v.event_format == EventFormatVersions.V1:
         pdus_to_check_event_id = [
             p for p in pdus_to_check
             if p.sender_domain != get_domain_from_id(p.pdu.event_id)
@@ -289,10 +293,6 @@ def _check_sigs_on_pdus(keyring, room_version, pdus):
 
         for p, d in zip(pdus_to_check_event_id, more_deferreds):
             p.deferreds.append(d)
-    elif room_version in (RoomVersions.V3,):
-        pass  # No further checks needed, as event IDs are hashes here
-    else:
-        raise RuntimeError("Unrecognized room version %s" % (room_version,))
 
     # replace lists of deferreds with single Deferreds
     return [_flatten_deferred_list(p.deferreds) for p in pdus_to_check]
diff --git a/synapse/federation/federation_client.py b/synapse/federation/federation_client.py
index 58e04d81ab..f3fc897a0a 100644
--- a/synapse/federation/federation_client.py
+++ b/synapse/federation/federation_client.py
@@ -25,12 +25,7 @@ from prometheus_client import Counter
 
 from twisted.internet import defer
 
-from synapse.api.constants import (
-    KNOWN_ROOM_VERSIONS,
-    EventTypes,
-    Membership,
-    RoomVersions,
-)
+from synapse.api.constants import EventTypes, Membership
 from synapse.api.errors import (
     CodeMessageException,
     Codes,
@@ -38,6 +33,11 @@ from synapse.api.errors import (
     HttpResponseException,
     SynapseError,
 )
+from synapse.api.room_versions import (
+    KNOWN_ROOM_VERSIONS,
+    EventFormatVersions,
+    RoomVersions,
+)
 from synapse.events import builder, room_version_to_event_format
 from synapse.federation.federation_base import FederationBase, event_from_pdu_json
 from synapse.util import logcontext, unwrapFirstError
@@ -570,7 +570,7 @@ class FederationClient(FederationBase):
             Deferred[tuple[str, FrozenEvent, int]]: resolves to a tuple of
             `(origin, event, event_format)` where origin is the remote
             homeserver which generated the event, and event_format is one of
-            `synapse.api.constants.EventFormatVersions`.
+            `synapse.api.room_versions.EventFormatVersions`.
 
             Fails with a ``SynapseError`` if the chosen remote server
             returns a 300/400 code.
@@ -592,7 +592,7 @@ class FederationClient(FederationBase):
 
             # Note: If not supplied, the room version may be either v1 or v2,
             # however either way the event format version will be v1.
-            room_version = ret.get("room_version", RoomVersions.V1)
+            room_version = ret.get("room_version", RoomVersions.V1.identifier)
             event_format = room_version_to_event_format(room_version)
 
             pdu_dict = ret.get("event", None)
@@ -695,7 +695,9 @@ class FederationClient(FederationBase):
             room_version = None
             for e in state:
                 if (e.type, e.state_key) == (EventTypes.Create, ""):
-                    room_version = e.content.get("room_version", RoomVersions.V1)
+                    room_version = e.content.get(
+                        "room_version", RoomVersions.V1.identifier
+                    )
                     break
 
             if room_version is None:
@@ -802,11 +804,10 @@ class FederationClient(FederationBase):
                     raise err
 
                 # Otherwise, we assume that the remote server doesn't understand
-                # the v2 invite API.
-
-                if room_version in (RoomVersions.V1, RoomVersions.V2):
-                    pass  # We'll fall through
-                else:
+                # the v2 invite API. That's ok provided the room uses old-style event
+                # IDs.
+                v = KNOWN_ROOM_VERSIONS.get(room_version)
+                if v.event_format != EventFormatVersions.V1:
                     raise SynapseError(
                         400,
                         "User's homeserver does not support this room version",
diff --git a/synapse/federation/federation_server.py b/synapse/federation/federation_server.py
index 81f3b4b1ff..df60828dba 100644
--- a/synapse/federation/federation_server.py
+++ b/synapse/federation/federation_server.py
@@ -25,7 +25,7 @@ from twisted.internet import defer
 from twisted.internet.abstract import isIPAddress
 from twisted.python import failure
 
-from synapse.api.constants import KNOWN_ROOM_VERSIONS, EventTypes, Membership
+from synapse.api.constants import EventTypes, Membership
 from synapse.api.errors import (
     AuthError,
     Codes,
@@ -34,6 +34,7 @@ from synapse.api.errors import (
     NotFoundError,
     SynapseError,
 )
+from synapse.api.room_versions import KNOWN_ROOM_VERSIONS
 from synapse.crypto.event_signing import compute_event_signature
 from synapse.events import room_version_to_event_format
 from synapse.federation.federation_base import FederationBase, event_from_pdu_json
diff --git a/synapse/federation/transport/server.py b/synapse/federation/transport/server.py
index efb6bdca48..452599e1a1 100644
--- a/synapse/federation/transport/server.py
+++ b/synapse/federation/transport/server.py
@@ -21,8 +21,8 @@ import re
 from twisted.internet import defer
 
 import synapse
-from synapse.api.constants import RoomVersions
 from synapse.api.errors import Codes, FederationDeniedError, SynapseError
+from synapse.api.room_versions import RoomVersions
 from synapse.api.urls import FEDERATION_V1_PREFIX, FEDERATION_V2_PREFIX
 from synapse.http.endpoint import parse_and_validate_server_name
 from synapse.http.server import JsonResource
@@ -513,7 +513,7 @@ class FederationV1InviteServlet(BaseFederationServlet):
         # state resolution algorithm, and we don't use that for processing
         # invites
         content = yield self.handler.on_invite_request(
-            origin, content, room_version=RoomVersions.V1,
+            origin, content, room_version=RoomVersions.V1.identifier,
         )
 
         # V1 federation API is defined to return a content of `[200, {...}]`